This invention relates generally to clamshell buckets for dredging silt and sediments disposed under a body of water, and more particularly to an apparatus and method for removing excess water contained in a loaded dredging bucket.
Dredging operations in harbors, rivers and the like are commonly employed to remove silt, sediments and hazardous waste materials that accumulate over time to create hazards in such bodies of water. Typically, clamshell type dredging buckets are used to dredge these materials, and place the same on barges, trucks and/or rail cars for shipment to another location for disposal. However, during the dredging operation, it is common for large amounts of water, in addition to solids, to be retained in the bucket, and shipped with the solids, thereby decreasing the efficiency of the dredging operation. Because the cost of sediment removal is based on either volume or weight, a substantial reduction in the amount of retained water can reduce the cost of such operations. For this reason, many configurations for dredging buckets have been introduced with varying degrees of success. For example, in 1990 a PCT patent publication by Bergeron disclosed a power bucket having a plurality of openings in the side walls disposed to adjust the volume carrying capability of the bucket. This design, however, does not adapt to varying levels of liquids retained in the dredging operation.
Similarly, in 1995 U.S. Pat. No. 5,477,627 issued disclosing an apparatus for dewatering peat moss material. This apparatus included a bucket that incorporates a press chamber for pressing the water and moisture from the peat moss. Because of its construction, this invention is not adaptable for the removal of sediments because the same would be expelled along with the water.
In 1996, U.S. Pat. No. 5,501,024 issued directed to a bucket that employs a swiper plate attached to one sidewall on each side of the bucket to prevent solids from escaping from the side walls as the bucket halves are closed. The problem with this design is that it is complicated, and the reduction of retained water is minimal.
Similar to the '627 patent noted above, U.S. Pat. No. 5,528,844 issued illustrating an excavating bucket employing a compression plate hydraulically activated to press the dredged contents to remove unwanted retained water. The problem with this design is that the material would require a consistency of peat moss to be effective.
Additionally, in 2002, U.S. Pat. No. 6,432,303 issued disclosing a sediment excavator that included a bucket disposed within a bucket to minimize the dispersion of particulate matter that occurs during the dredging operation. Likewise, this design is cumbersome and provides only a minimal reduction is retained water.
Importantly, most of the above noted designs do not adequately address the problems associated with large amount of retained water that will be transported away from the dredging site along with the dredged solid materials. Because the cost of shipping and disposing of the dredged material is high, a reduction in the amount of retained water that is shipped can substantially reduce the cost of dredging.
Accordingly, a need remains for a cost effective method and apparatus to substantially reduce the amount of retained water that is present in dredging operations. For this purpose, an improved dewatering system for dredging buckets is provided.